db4o：如何在没有c＃原始类的情况下从数据库检索对象？

Question

I have db4o file created by some App (which I don't have source for) and I need to get all the data from this file.

In all examples I saw in tutorials there were Classes used for retrieving objects but what to do if I don't have these classes?

Answer 1

You can try it with LINQPad and my driver: http://www.gamlor.info/wordpress/2011/03/db4o-driver-for-linqpad/

Otherwise, you can explore the db4o reflection API:

Assuming you have no class, and just want to see everything. Something like this (don't remember the exact API):

IQuery query = container.Query();
IEnumerable allObjects = query.Execute();

foreach(Object item : allObjects){

    GenericObject dbObject = (GenericObject)item; // Note: If db4o finds actuall class, it will be the right class, otherwise GenericObject. You may need to do some checks and casts
    dbObject.GetGenericClass().GetDeclaredFields(); // Find out fields
    object fieldData = dbObject.Get(0); // Get the field at index 0. The GetDeclaredFields() tells you which field is at which index
}